Laminated coating head

ABSTRACT

A coating head for noncontacting coating apparatus in which the majority of the components of the head are manufactured separately as platelike members and then assembled in the proper order in laminar form to provide a laminated coating head.

United States Patent Dale R. Beam;

Inventors Russell H. Van Brimer, both 01 Chillicothe, Ohio Appl. No.877,250 Filed Nov. 17, 1969 Patented June 22, 1971 Assignee The MeadCorporation Dayton, Ohio LAMINATED COATING HEAD 14 Claims, 6 DrawingFigs.

US. Cl 317/3, 346/75, 239/15 Int. Cl ..G0ld 15/18, B05b 5/00, B05b 5/02Field of Search 31 3,

[5 6] References Cited UNITED STATES PATENTS 2,628,150 2/1953 Gunderson346/75 3,278,940 10/1966 Ascoli 346/75 3,298,030 1/1967 Lewis et 346/753,373,437 3/1968 Sweet etal 317/3 X 3,458,761 7/1969 Ascoli 317/33,512,173 5/1970 Damouth 346/75 Primary Examiner-Lee T. l-lixAttorney-Marechal, Biebel, French and Bugg ABSTRACT: A coating head fornoncontacting coating apparatus in which the majority of the componentsof the head are manufactured separately as platelike members and thenassembled in the proper order in laminar form to provide a laminatedcoating head.

PATENTED JUN22 I97! l/V VE IV TORS DALE R. BEAM 8 RUSSELL H. VAN BRIMERATTORNEYS LAMINATED COATING HEAD CROSS REFERENCE TO RELATED APPLICATIONIMAGE CONSTRUCTION SYSTEM USING MULTIPLE ARRAYS OF DROP GENERATORS, Ser.No. 768,790 filed Oct. 18, I968.

BACKGROUND OF THE INVENTION In the above noted, related application, asystem is disclosed for applying a coating to a moving web or the likewithout contact between the coating apparatus and the material to becoated. It should be noted that the term coating is used herein in itsbroader's'ense to include patterned coating, as in printing, as well asthe application of a continuous layer of coating. Coating apparatusconstructed in accordance with the above noted related applicationdivides a supply of coating material into a series of discrete jetswhich tend to break down into a series of small drops. The drops arethen directed through a charge ring which may be selectively activatedto either impart or not impart an electrostaticcharge to each drop. Thedrops then pass through an electrostatic field and are eitherdeflected-or not deflected depending upon whether or not they have beencharged by the charge rings. A catcher is pro- 'videdbeneath theelectrostatic field and prevents drops which are deflected by the fieldfrom impinging upon-the web or other article being coated. Thus, bycontrolling the electric signals to the charge rings, drops of coatingmaterial can be deposited on theweb or other article to be treated inany desired pattern.

It will be apparent that in a coating system of the type described abovethe dimensions of components must be controlled with great precision.For example, the charge ring through which the droplets pass may be onthe order of 0.023 inches in diameter while the orifices from which thecoating material is ejected may be only 0.0015 inches in diameter.

Additionally, it will be seen that relatively small particles of foreignmaterial could cause a malfunction if they became lodged in the systemduring either the manufacture thereof or as a result of impurities inthe coating material.

It will also be apparent that when dealing with a system in which thecomponents must be dimensioned within extremely fine tolerance limits,any modification of these dimensions through a build up of coatingmaterial could seriously affect the operation of the system. It istherefore desirable, if not necessary, that some provision be made forexpeditiously cleaning the coating head between operations.

The environment in which coating systems of the type described above maybe used to great advantage is in the application of coating material toa moving web of paper or the like, and in this type of operation it isnecessary that the coating head'be suspended over the moving web. It istherefore, desirable to keep the coating head as compact as possible.

SUMMARY OF THE INVENTION In accordance with the present invention thecomponents of the coating head are each manufactured separately and thenjoined in laminar relationship to form the completed coating head. Inthis way, each of the components may be manufactured with the degree ofprecision required for successful operation of the system. Constructingthe coating head as an assembly of components also renders the task ofinsuring that each of the components is free of foreign material lesscomplicated than would be the case if it were attempted to construct theprinting head as a single unit or one or two subunits.

Additionally, should it become necessary to remove foreign material fromthe printing head, the head may be readily dismantled and each componentcarefully cleaned. In this regard it should also be noted that thelaminar construction of the printing head permits the incorporation of afilter in the printing head immediately upstream of the orifices throughwhich the coating is ejected. In this way foreign materials BRIEFDESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded perspective viewshowing the various components of one form of laminated coating head;

FIG. 2 is a cross-sectional view through a second form of coating headwith the section through one portion thereof as taken on line A-A ofFIG. 3;

FIG. 3 is a plan view of an inlet plate utilized in the presentinvention; I

FIG. 4 is a plan view of the upper surface of the clamp plate;

FIG. 5 is an enlargement of a portion of FIG. 2 showing a portion of theconstruction of F IG. 2 in more detail; and

FIG. 6 is a partialplan view of a portion of a charge ring plate. I

DESCRIPTION OF TI IE PREFERRED EMBODIMENTS As seen in FIGS. 1 and 2, thelaminated printing head comprises a manifold 10 having a chamber 11therein extending longitudinally of the manifold and opening outwardly,as at 12, along one portion thereof and a. conduit 13 for deliveringcoating material to the chamber 11. A filter plate 20 having a centralportion 21 provided with-a series of very fine perforations therethroughis positioned with its perforated central portion over the opening 12and a gasket member 23 interposed between the lower surface of themanifold 10 and the upper surface of the filter 20.

A second gasket member 24 and an inlet plate 30 are positioned beneaththe filter plate 20 and, as best seen in FIG. 3, the inlet plate has anelongated slot 31 formed in one surface thereof extending longitudinallyof the inlet plate and facing the opening 12 in the manifold 10. Aseries of uniformly spaced passages 32 are formed in the inlet plateextending from the bottom wall 33 of the slot 31 to the lower surface 34of the inlet plate. Adjacent one end of the inlet plate a cleanout port35 formed extending from one side of the plate into the slot 31 and acover plate 36 and gasket 37 are secured over port 35 by means of boltsor the like 38.

Immediately beneath the inlet plate 30 an orifice plate 40 is positionedhaving a, series of openings 41 formed therein at regularly spacedintervals in substantial concentricity with the apertures 32 in theplate 30. A spacer plate 42 having a series of openings 43 formedtherein in line with openings 41 is mounted beneath orifice plate 40 andserves to space a charge ring plate 50 from orifice plate 40apredetermined distance for a purpose to be presently described.

The charge ring plate 50, formed of a dielectric material, is positionedbeneath the spacer plate 42 and is provided with a series of openings 5]extending therethrough, concentric with and appreciably greater indiameter than, the orifices 41. A discrete application of anelectrically conductive coating material surrounds each opening 51, incircular outline, and covers the wall thereof to form a charge ring 52(FIG. 5). Also applied to the plate 50 are a series of discrete lines ofelectrically conductive coating material which form conductors extendingfrom each charge ring 52 t o a connector 54 mounted on charge ring plate50 adjacent each end of a clamp plate 60. Connectors 54 engagecomplementary connectors 55, which in turn are in circuit with controlunit 56 by means of cables 57. The charge rings 52 and conductors 53 canquite conveniently be manufactured using conventional printed circuittechniques although it will be appreciated that a somewhat higher degreeof precision will be required than is usually necessary in printedcircuit manufacture.

The clamp plate 60, similarly to the plates 30, 40 and 50, has a seriesof openings 61 extending therethrough which are substantially concentricwith the openings 32, 41 and 51.

A pair of electrodes 70 are attached to the lower surface 63 of theclamp plate 60 by means of a pair of pins 71 having enlarged portions 72attached to each of the electrodes 70 and abutting the lower surface 63by means of the shoulder 73 formed by the enlarged portion. Each of theelectrodes may conveniently e constructed of a resin impregnated fibrousmaterial and provided with a coating of an electrically conductivematerial 74 along opposing faces thereof. For a purpose to be presentlyexplained, each of the electrodes 70 is formed throughout a majorportion of its length with triangularly shaped cross section 75 whiledistal portions 76 of each electrode are of rectangular cross sectionand receive the lower ends of the pins 72. It will also be noted thatthe lower outermost corner of each of the electrodes is beveled as at 77and that leads 78 are attached to the'electrically conductive coatings74 and to a source ofelectrical energy 79.

A pair of brackets 80 are also attached to the lower surface 63 of theclamp plate 60 and extend downwardly to support the catcher 81 having ablade 82 projecting outwardly thereof and at a slight angle to thehorizontal. At least the upper surface and preferably both surfaces ofthe blade 82 are covered with a porous material, such as screening, topermit any drops of coating material which strike the blade to moveinwardly into the interior of the catcher 81 from whence they areevacuated by the vacuum pump 83. The bracket 80 is preferably providedwith adjusting means to permit limited movement of the catchertransversely of the coating head.

As best seen in FIG. 2, the manifold 'and the plate members 30, 40, 50and 60 are provided with a series of aligned bolt holes 90 along theiredges to provide a series of continuous passages 91 through thecomponents of the coating head for reception of the assembly bolts 92.Bolts 92 have threaded ends 93 and clamp plate 60 is provided withthreaded openings 94.

In operation, coating material is delivered through the conduit 13 intothe chamber 11 of the manifold and thence out through the opening 12 andthe filter plate 20. The filter plate serves to screen out any particleswhich may be large enough to obstruct orifices 41 during passagetherethrough. By positioning the filter plate in proximity to theorifice plate, the danger of coating material having foreign particlestherein reaching and clogging the orifices in the plate is reduced to aminimum. While from a filtering standpoint, it would be most desirableto have the filter plate immediately upstream of the orifices 41, itwill be appreciated that faceto-face contact betweenfilter plate 20 andorifice plate 40 might result in partial blockage of orifices 41.Therefore, the inlet plate 30, with the chamber provided by the slot 31,is positioned between the filter and the orifice plate. Additionally, tochannel the flow from the slot 31 and inhibit the formation of crossflows, the coating material is delivered from the slot 31 to theorifices 41 by means of the passages 32.

As the coating material passes through the orifices 41, there is anatural tendency for each of the jets to break into a series of finedrops. However, these drops would not be generated naturally at auniform rate nor would they normally be of a uniform size. Therefore, toinsure uniformity an externalstimulation is applied to the coating head.As seen in FIG. 1 of the drawings, this may take the form of a sonicvibrator 100 attached to the manifold 10 and imposing a sonic signal ofa predetermined frequency on the system Alternatively, the signal may bean electric signal applied to the jets as they leave the orifices 41 bymeans of an electrohydrodynamic plate 101 (FIG. 2) which may besubstituted for spacer plate 42 (FIG. 1) and which may have a series ofopenings 102 formed therethrough. Electrohydrodynamic plate 101 ispreferably provided with an electrically conductive coating on the uppersurface thereof and an insulating coating over the electricallyconductive coating. Stimulation is achieved by connecting the conductivecoating to an oscillating voltage source and thereby producing tractionforces at the surfaces of the unbroken fluid filaments.

In either case, a series of drops of uniform size are projected fromeach of the orifices 41 at a uniform rate and pass through the chargerings 52 in charge plate 50. Control unit 56 controls the charge rings52 and causes each drop passing through each of the charge rings to becharged or not, as desired. If a drop is charged, as it passes betweenthe electrodes 70 it will be deflected from its normally vertical path aslight amount, to the right as seen in FIG. 2, where it is caught by theblade 82 of the catcher 81. Conversely, if the charge ring does notcharge a particular drop it will continue in a substantially verticalpath and be imprinted on the web or the like W.

It should also be noted that is is desirable to charge the drops justbefore they break away from their respective jets. The point at whichthey break away will vary, of course, under different operatingconditions but will generally occur a short distance downstream of theoutlets of the orifices 41. Therefore, the thickness of spacer plate 42(or electrohydrodynamic plate 101 as the case may be) is selected toposition charge ring plate 50 at the jet breakup point. Minor variationsin the breakup position are compensated for by extending each chargering 52 to cover the entire wall of its corresponding opening 51.

In a typical installation, the screen 20 is 0.001 inches thick and thecentral portion thereof provided with 41,000 holes of one-half mil indiameter and arranged in a 90 array. The inlet plate is 0.250 inchesthick and has 50 passages 32, each 0.0635 inches in diameter and spacedon 0.1000 inch centers. The orifice plate is 0.011 inches in thicknessand is provided with 50 orifices of 1.5 mils in diameter. If anelectrohydrodynamic plate 101 is utilized, this plate may be 0.105inches in thickness and have a series of 50 openings therethrough of0.040 inches in diameter. The charge ring plate is 0.093 inches thickand also has 50 holes 51 therethrough of 0.025 inches in diameter.

The clamp plate 60, which also serves as an insulating shield betweenthe charge ring plate and the electrodes 70, may be seven sixty-fourthsof an inch in thickness with 50 openings 0.0635 inches in diameterextending therethrough. The electrodes may be 0.500 inches in thicknessand spaced apart a distance of 0.065 inches.

As best seen in FIG. 2, the web W of paper or the like is trained pastthe coating head at an appreciable angle to the horizontal. Thisarrangement lessens the tendency of the droplets projected onto the webto assume a noncircular shape and gives a more symmetrical imprint. Inthis regard, the corners of the electrodes are beveled as at 77 topermit the coating head to be positioned beveling of the right-handelectrode as seen in FIG. 1 has no effect upon the proximity of thecoating head to the web, it will be appreciated that by manufacturingall electrodes identically the necessity for stocking two differenttypes of electrodes is eliminated.

In assembly the coating head, the filter plate 20, inlet plate 30 andorifice plate 40 are assembled on a jig in proper position with respectto each other. A cleaning fluid is then pumped through the filter plate20 and into the slot 31 and compressed air is pumped through theorifices 41; the air and cleaning fluid exiting the inlet plate throughthe cleanout port 35. After these three components have been cleaned inthis manner, the cover plate 36 is attached to the inlet plate and theremaining components of the coating head stacked on a jig in theirproper position with respect to each other. Bolts 92 are then placed ineach of the passages 91 with the screwthreaded lower end 93 of each boltengaging complementary threads 94 in the openings in the clamp plate.The electrodes are then attached to the assembly by inserting the pin71, which is coated with a resilient material, into the openings in thelower surface of the clamp plate where they frictionally engage thewalls of the openings. The catcher 81 is next attached to the clampplate and precisely positioned by means of the brackets just to oneside, the right-hand side as seen in FIG. 2, of the path thenondeflected drops take from the orifice 41. It will be noted that byforming the electrodes 75 as triangular in cross section throughout mostof their extent, the space between the electrodes and the bottom of theclamp plate 60 may be readily cleaned.

From the above if will be seen that the present invention provides alaminated coating head in which each of the components thereof may bemanufactured separately with the high degree of precision necessary fora system of this type. Additionally, the system may be readily cleanedboth before assembly and after, and means are provided for filtering thecoating material immediately upstream of a majority of the components ofthe coating head. It will also be noted that the unit is exceptionallycompact and therefore ideally suited for suspension over a moving web orthe like and yet may be readily dismantled if necessary for cleaning andrepair.

While the forms of apparatus herein described constitute preferredembodiments of the invention, it is to be understood that the inventionis not limited to these precise forms of apparatus, and that changes maybe made therein without departing from the scope of the invention whichis defined in the appended claims.

What I claim is:

l. A laminated coating head comprising:

a. an orifice plate having a series of regularly spaced orifices Iformed therethrough,

b. means for supplying fluid under pressure to each of said orifices,

c. a charge ring plate extending coextensively with one surface of saidorifice plate and having a series of openings therethrough concentricwith said orifices,

d. a charge ring positioned in each of said charge ring plate openings,

e. means for selectively applying an electrical charge to each of saidcharge rings,

. means for securing said fluid supplying means, orifice plate andcharge rig plate together in laminar relationship,

g. means for establishing an electrostatic field beneath said chargering plate, and

h. means for catching drops of fluid ejected through said orifices.

2. The apparatus of claim 1 further comprising:

a. a filter interposed between said fluid supplying means and saidorifice plate.

3. The apparatus of claim 1 further comprising:

a. an inlet plate interposed between said fluid supplying means and saidorifice plate,

b. said inlet plate having an elongated slot formed in a surface thereofadjacent said fluid supplying means.

4. The apparatus of claim 1 further comprising:

a. an electrohydrodynamic plate interposed between said orifice plateand said charge ring plate,

b. said electrohydrodynamic plate having a series of openingstherethrough concentric with said orifices, and

c. means for applying an electrical signal of a predetermined frequencyto said electrohydrodynamic plate.

5. The apparatus of claim 1 wherein said means for establishing anelectrostatic field comprises:

a. a pair of elongated electrodes, and

b. means mounting said electrodes in spaced relationship to a lowerportion of said coating head and in parallel spaced relation to eachother.

6. The apparatus of claim 5 wherein:

a. each of said electrodes is of substantially triangular cross sectionthroughout a major portion of its length.

7. The apparatus of claim 6 wherein:

a. distal portions of said electrodes are substantially rectangular incross section, and

b. said mounting means extends from said distal portions to said lowerportion of said coating head.

8. A laminated coating head comprising:

a. a coating material manifold having means defining a chamber thereinextending longitudinally of said coating head and opening outwardlyalong a portion thereof,

b. an inlet plate extending coextensively with said manifold and havingan elongated slot in one surface thereof facing said manifold opening,

. a filter plate interposed between said manifold and said inlet plate,

(1. a cleanout opening having a removable cover thereover extending fromone side of said inlet plate into said slot,

e. an orifice plate abutting said opposite surface of said inlet plateand extending coextensive therewith,

f. said orifice plate having a series of orifices therein,

g. a charge ring plate extending beneath one surface of said orificeplate and having a series of openings thcrethrough concentric with saidorifices,

h. a charge ring positioned in each of said charge ring plate openings,

. a clamp plate abutting one surface of said charge ring plate andhaving a series of openings therethroug'h concentric with said chargering plate openings,

k. fastener means extending from said manifold to said clamp plate andsecuring said manifold, inlet plate, filter plate, orifice plate, chargering and clamp plate together in laminar relationship,

I. a pair of electrodes attached to a lower surface of said clamp plate,and

m. a catcher attached to said lower surface of said clamp plate andextending beneath said electrode.

9. The apparatus of claim 8' further comprising:

a. an electrohydrodynamic plate positioned between said clamp plate andsaid orifice plate,

b. a series of openings in said electrohydrodynamic plate concentricwith said orifices,

c. means for applying an electric signal of a predetermined frequency tosaid electrohydrodynamic plate.

10. Apparatus for imparting an electric charge to individual drops ofcoating comprising:

a. an elongated plate member of dielectric material,

b. means defining a series of regularly-spaced openings through saidplate member,

c. a discrete application of electrically conductive materialsurrounding each of said openings, and

d. a conductor extending from each of said discrete applications to asource of electric energy.

11. The apparatus ofclaim 10 wherein:

a. said electrically conductive material extends into and covers thewall of each of said openings but does not block said openings.

12. The apparatus of claim 11 wherein:

a. each of said discrete applications is substantially circular inoutline.

13. The apparatus of claim 10 wherein:

a. each of said conductors comprises a line of electrically conductivematerial applied to said plate member.

14. The apparatus of claim 10 further comprising:

a. means for selectively energizing each of said discrete applicationsof electrically conductive material.

1. A laminated coating head comprising: a. an orifice plate having aseries of regularly spaced orifices formed therethrough, b. means forsupplying fluid under pressure to each of said orifices, c. a chargering plate extending coextensively with one surface of said orificeplate and having a series of openings therethrough concentric with saidorifices, d. a charge ring positioned in each of said charge ring plateopenings, e. means for selectively applying an electrical charge to eachof said charge rings, f. means for securing said fluid supplying means,orifice plate and charge rig plate together in laminar relationship, g.means for establishing an electrostatic field beneath said charge ringplate, and h. means for catching drops of fluid ejected through saidorifices.
 2. The apparatus of claim 1 further comprising: a. a filterinterposed between said fluid supplying means and said orifice plate. 3.The apparatus of claim 1 further comprising: a. an inlet plateinterposed between said fluid supplying means and said orifice plate, b.said inlet plate having an elongateD slot formed in a surface thereofadjacent said fluid supplying means.
 4. The apparatus of claim 1 furthercomprising: a. an electrohydrodynamic plate interposed between saidorifice plate and said charge ring plate, b. said electrohydrodynamicplate having a series of openings therethrough concentric with saidorifices, and c. means for applying an electrical signal of apredetermined frequency to said electrohydrodynamic plate.
 5. Theapparatus of claim 1 wherein said means for establishing anelectrostatic field comprises: a. a pair of elongated electrodes, and b.means mounting said electrodes in spaced relationship to a lower portionof said coating head and in parallel spaced relation to each other. 6.The apparatus of claim 5 wherein: a. each of said electrodes is ofsubstantially triangular cross section throughout a major portion of itslength.
 7. The apparatus of claim 6 wherein: a. distal portions of saidelectrodes are substantially rectangular in cross section, and b. saidmounting means extends from said distal portions to said lower portionof said coating head.
 8. A laminated coating head comprising: a. acoating material manifold having means defining a chamber thereinextending longitudinally of said coating head and opening outwardlyalong a portion thereof, b. an inlet plate extending coextensively withsaid manifold and having an elongated slot in one surface thereof facingsaid manifold opening, c. a filter plate interposed between saidmanifold and said inlet plate, d. a cleanout opening having a removablecover thereover extending from one side of said inlet plate into saidslot, e. an orifice plate abutting said opposite surface of said inletplate and extending coextensive therewith, f. said orifice plate havinga series of orifices therein, g. a charge ring plate extending beneathone surface of said orifice plate and having a series of openingstherethrough concentric with said orifices, h. a charge ring positionedin each of said charge ring plate openings, i. a clamp plate abuttingone surface of said charge ring plate and having a series of openingstherethrough concentric with said charge ring plate openings, k.fastener means extending from said manifold to said clamp plate andsecuring said manifold, inlet plate, filter plate, orifice plate, chargering and clamp plate together in laminar relationship, l. a pair ofelectrodes attached to a lower surface of said clamp plate, and m. acatcher attached to said lower surface of said clamp plate and extendingbeneath said electrode.
 9. The apparatus of claim 8 further comprising:a. an electrohydrodynamic plate positioned between said clamp plate andsaid orifice plate, b. a series of openings in said electrohydrodynamicplate concentric with said orifices, c. means for applying an electricsignal of a predetermined frequency to said electrohydrodynamic plate.10. Apparatus for imparting an electric charge to individual drops ofcoating comprising: a. an elongated plate member of dielectric material,b. means defining a series of regularly-spaced openings through saidplate member, c. a discrete application of electrically conductivematerial surrounding each of said openings, and d. a conductor extendingfrom each of said discrete applications to a source of electric energy.11. The apparatus of claim 10 wherein: a. said electrically conductivematerial extends into and covers the wall of each of said openings butdoes not block said openings.
 12. The apparatus of claim 11 wherein: a.each of said discrete applications is substantially circular in outline.13. The apparatus of claim 10 wherein: a. each of said conductorscomprises a line of electrically conductive material applied to saidplate member.
 14. The apparatus of claim 10 further comprising: a. meansfor selectively energizing each of said disCrete applications ofelectrically conductive material.